Created attachment 94929 [details]
Screenshot of issue

I have code:

var foo = ["aaa", "bbb", "ccc"];
foo.reduce(function(previousValue, currentValue, index, array) {
    return previousValue + currentValue;
}, "");

The area within the reduce() brackets (including the "" argument) is highlighted green with the following tooltip:

Problem in Semantic analysis:
Possible type mismatch between the argument type (function void ()) and the value passed as argument (function mixed (mixed, mixed, mixed, mixed))

Obviously the first argument to reduce() can't be void.tg